Added a deactivate() function to Tab so when switching tabs it hides … (#5386)

Added a deactivate() function to Tab so when switching tabs it hides the active contents. Also removed clearing of the pages so it's not destroyed each time.

Co-authored-by: SoftFever <softfeverever@gmail.com>

src/slic3r/GUI/Tab.hpp

@@ -104,6 +104,7 @@ public:
 	void		reload_config();
     void        update_visibility(ConfigOptionMode mode, bool update_contolls_visibility);
     void        activate(ConfigOptionMode mode, std::function<void()> throw_if_canceled);
+    void        deactivate();
     void        clear();
     void        msw_rescale();
     void        sys_color_changed();